Using various techniques of RNA/DNA hybridization, this project will continue defining the key alterations of gene regulation which are common to malignant tumors induced by chemicals, viruses, and radiation, and promoted by chemicals, hormones, injury, or other factors. Experiments characterizing altered transport of RNA to the cytoplasm after X-irradiation or hormone treatment will be completed and correlated with data from chemical and viral induction of this defect. The RNAs transported to the rat liver cytoplasm only after carcinogen exposure will be characterized by size, rate of degradation, relation to other nuclear RNAs, and time of attachment to polysomes. Correlations will be determined between loss of transcription of repetitive and nonrepetitive sequences during serial transplant of tumors, between loss of transcription and tumor growth rate and metastasis, and between base sequences repressed during serial transplant from tumors of common origin.